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, Available online 12 September 2024,
https://doi.org/10.1007/s12613-024-3006-5
Abstract:
Ti–6Al–4Zr–2Sn–6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion–laser beam (PBF–LB) technology. This alloy has the potential to replace Ti–6Al–4V in automotive and aerospace applications, given its superior mechanical properties, which are approximately 10% higher in terms of ultimate tensile strength (UTS) and yield strength after appropriate heat treatment. In as-built conditions, the alloy is characterized by the presence of soft orthorhombic α″ martensite, necessitating a postprocessing heat treatment to decompose this phase and enhance the mechanical properties of the alloy. Usually, PBFed Ti6246 components undergo an annealing process that transforms the α″ martensite into an α–β lamellar microstructure. The primary objective of this research was to develop a solution treatment and aging (STA) heat treatment tailored to the unique microstructure produced by the additive manufacturing process to achieve an ultrafine bilamellar microstructure reinforced by precipitation hardening. This study investigated the effects of various solution temperatures in the α–β field (ranging from 800 to 875°C), cooling media (air and water), and aging time to determine the optimal heat treatment parameters for achieving the desired bilamellar microstructure. For each heat treatment condition, different α–β microstructures were found, varying in terms of the α/β ratio and the size of the primary α-phase lamellae. Particular attention was given to how these factors were influenced by increases in solution temperature and how microhardness correlated with the percentage of the metastable β phase present after quenching. Tensile tests were performed on samples subjected to the most promising heat treatment parameters. A comparison with literature data revealed that the optimized STA treatment enhanced hardness and UTS by 13% and 23%, respectively, compared with those of the annealed alloy. Fracture surface analyses were conducted to investigate fracture mechanisms.
Ti–6Al–4Zr–2Sn–6Mo alloy is one of the most recent titanium alloys processed using powder bed fusion–laser beam (PBF–LB) technology. This alloy has the potential to replace Ti–6Al–4V in automotive and aerospace applications, given its superior mechanical properties, which are approximately 10% higher in terms of ultimate tensile strength (UTS) and yield strength after appropriate heat treatment. In as-built conditions, the alloy is characterized by the presence of soft orthorhombic α″ martensite, necessitating a postprocessing heat treatment to decompose this phase and enhance the mechanical properties of the alloy. Usually, PBFed Ti6246 components undergo an annealing process that transforms the α″ martensite into an α–β lamellar microstructure. The primary objective of this research was to develop a solution treatment and aging (STA) heat treatment tailored to the unique microstructure produced by the additive manufacturing process to achieve an ultrafine bilamellar microstructure reinforced by precipitation hardening. This study investigated the effects of various solution temperatures in the α–β field (ranging from 800 to 875°C), cooling media (air and water), and aging time to determine the optimal heat treatment parameters for achieving the desired bilamellar microstructure. For each heat treatment condition, different α–β microstructures were found, varying in terms of the α/β ratio and the size of the primary α-phase lamellae. Particular attention was given to how these factors were influenced by increases in solution temperature and how microhardness correlated with the percentage of the metastable β phase present after quenching. Tensile tests were performed on samples subjected to the most promising heat treatment parameters. A comparison with literature data revealed that the optimized STA treatment enhanced hardness and UTS by 13% and 23%, respectively, compared with those of the annealed alloy. Fracture surface analyses were conducted to investigate fracture mechanisms.
, Available online 10 September 2024,
https://doi.org/10.1007/s12613-024-3003-8
Abstract:
The feasibility of manufacturing Ti–6Al–4V samples through a combination of laser-aided additive manufacturing with powder (LAAMp) and wire (LAAMw) was explored. A process study was first conducted to successfully circumvent defects in Ti–6Al–4V deposits for LAAMp and LAAMw, respectively. With the optimized process parameters, robust interfaces were achieved between powder/wire deposits and the forged substrate, as well as between powder and wire deposits. Microstructure characterization results revealed the epitaxial prior β grains in the deposited Ti–6Al–4V, wherein the powder deposit was dominated by a finer α′ microstructure and the wire deposit was characterized by lamellar α phases. The mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and discussed. The mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications (AMS 6932) even without post heat treatment. No fracture occurred within the interfacial area, further suggesting the robust interface. The findings of this study highlighted the feasibility of combining LAAMp and LAAMw in the direct manufacturing of Ti–6Al–4V parts in accordance with the required dimensional resolution and deposition rate, together with sound strength and ductility balance in the as-built condition.
The feasibility of manufacturing Ti–6Al–4V samples through a combination of laser-aided additive manufacturing with powder (LAAMp) and wire (LAAMw) was explored. A process study was first conducted to successfully circumvent defects in Ti–6Al–4V deposits for LAAMp and LAAMw, respectively. With the optimized process parameters, robust interfaces were achieved between powder/wire deposits and the forged substrate, as well as between powder and wire deposits. Microstructure characterization results revealed the epitaxial prior β grains in the deposited Ti–6Al–4V, wherein the powder deposit was dominated by a finer α′ microstructure and the wire deposit was characterized by lamellar α phases. The mechanisms of microstructure formation and correlation with mechanical behavior were analyzed and discussed. The mechanical properties of the interfacial samples can meet the requirements of the relevant Aerospace Material Specifications (AMS 6932) even without post heat treatment. No fracture occurred within the interfacial area, further suggesting the robust interface. The findings of this study highlighted the feasibility of combining LAAMp and LAAMw in the direct manufacturing of Ti–6Al–4V parts in accordance with the required dimensional resolution and deposition rate, together with sound strength and ductility balance in the as-built condition.
, Available online 23 August 2024,
https://doi.org/10.1007/s12613-024-2992-7
Abstract:
Delafossite AgFeO2 nanoparticles with a mixture of 2H and 3R phases were successfully fabricated by using a simple co-precipitation method. The resulting precursor was calcined at temperatures of 100, 200, 300, 400, and 500°C to obtain the delafossite AgFeO2 phase. The morphology and microstructure of the prepared AgFeO2 samples were characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 adsorption/desorption, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) techniques. A three-electrode system was employed to investigate the electrochemical properties of the delafossite AgFeO2 nanoparticles in a 3 M KOH electrolyte. The delafossite AgFeO2 nanoparticles calcined at 100°C (AFO100) exhibited the highest surface area of 28.02 m2∙g−1 and outstanding electrochemical performance with specific capacitances of 229.71 F∙g−1 at a current density of 1 A∙g−1 and 358.32 F∙g−1 at a scan rate of 2 mV∙s−1. This sample also demonstrated the capacitance retention of 82.99% after 1000 charge/discharge cycles, along with superior specific power and specific energy values of 797.46 W∙kg−1 and 72.74 Wh∙kg−1, respectively. These findings indicate that delafossite AgFeO2 has great potential as an electrode material for supercapacitor applications.
Delafossite AgFeO2 nanoparticles with a mixture of 2H and 3R phases were successfully fabricated by using a simple co-precipitation method. The resulting precursor was calcined at temperatures of 100, 200, 300, 400, and 500°C to obtain the delafossite AgFeO2 phase. The morphology and microstructure of the prepared AgFeO2 samples were characterized by using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), N2 adsorption/desorption, X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS) techniques. A three-electrode system was employed to investigate the electrochemical properties of the delafossite AgFeO2 nanoparticles in a 3 M KOH electrolyte. The delafossite AgFeO2 nanoparticles calcined at 100°C (AFO100) exhibited the highest surface area of 28.02 m2∙g−1 and outstanding electrochemical performance with specific capacitances of 229.71 F∙g−1 at a current density of 1 A∙g−1 and 358.32 F∙g−1 at a scan rate of 2 mV∙s−1. This sample also demonstrated the capacitance retention of 82.99% after 1000 charge/discharge cycles, along with superior specific power and specific energy values of 797.46 W∙kg−1 and 72.74 Wh∙kg−1, respectively. These findings indicate that delafossite AgFeO2 has great potential as an electrode material for supercapacitor applications.
, Available online 26 July 2024,
https://doi.org/10.1007/s12613-024-2978-5
Abstract:
Silver nanoparticles (Ag NPs) have attracted attention in the field of biomaterials due to their excellent antibacterial property. However, the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water pollution. In this work, Ag NPs (31.2 nm in diameter) were prepared using the extract of straw, an agricultural waste, as the reducing and stabilizing agent. Experimental analysis revealed that the straw extract contained lignin, the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag NPs. The surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their aggregation. After the prepared Ag NPs were added to the precursor solution of acrylamide, free radical polymerization was triggered without the need for extra heating or light irradiation, resulting in the rapid formation of an Ag NP–polyacrylamide composite hydrogel. The inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag NPs. The prepared hydrogel may have potential applications in the fabrication of biomedical materials, such as antibacterial dressings.
Silver nanoparticles (Ag NPs) have attracted attention in the field of biomaterials due to their excellent antibacterial property. However, the reducing and stabilizing agents used for the chemical reduction of Ag NPs are usually toxic and may cause water pollution. In this work, Ag NPs (31.2 nm in diameter) were prepared using the extract of straw, an agricultural waste, as the reducing and stabilizing agent. Experimental analysis revealed that the straw extract contained lignin, the structure of which possesses phenolic hydroxyl and methoxy groups that facilitate the reduction of silver salts into Ag NPs. The surfaces of Ag NPs were negatively charged due to the encapsulation of a thin layer of lignin molecules that prevented their aggregation. After the prepared Ag NPs were added to the precursor solution of acrylamide, free radical polymerization was triggered without the need for extra heating or light irradiation, resulting in the rapid formation of an Ag NP–polyacrylamide composite hydrogel. The inhibition zone test proved that the composite hydrogel possessed excellent antibacterial ability due to the presence of Ag NPs. The prepared hydrogel may have potential applications in the fabrication of biomedical materials, such as antibacterial dressings.
, Available online 5 July 2024,
https://doi.org/10.1007/s12613-024-2968-7
Abstract:
Nowadays, force sensors play an important role in industrial production, electronic information, medical health, and many other fields. Two-dimensional material-based filed effect transistor (2D-FET) sensors are competitive with nano-level size, lower power consumption, and accurate response. However, few of them has the capability of impulse detection, which is a path function, expressing the cumulative effect of the force on the particle over a period of time. Herein, we fabricated the flexible polymethyl methacrylate (PMMA) gate dielectric MoS2-FET for force and impulse sensor application. We systematically investigated the responses of the sensor to constant force and varying forces, and achieved the conversion factors of the drain current signals (Ids) to the detected impulse (\begin{document}$ \overrightarrow{I} $\end{document}
Nowadays, force sensors play an important role in industrial production, electronic information, medical health, and many other fields. Two-dimensional material-based filed effect transistor (2D-FET) sensors are competitive with nano-level size, lower power consumption, and accurate response. However, few of them has the capability of impulse detection, which is a path function, expressing the cumulative effect of the force on the particle over a period of time. Herein, we fabricated the flexible polymethyl methacrylate (PMMA) gate dielectric MoS2-FET for force and impulse sensor application. We systematically investigated the responses of the sensor to constant force and varying forces, and achieved the conversion factors of the drain current signals (Ids) to the detected impulse (
, Available online 13 June 2024,
https://doi.org/10.1007/s12613-024-2955-z
Abstract:
Sinter is the core raw material for blast furnaces. Flue pressure, which is an important state parameter, affects sinter quality. In this paper, flue pressure prediction and optimization were studied based on the shapley additive explanation (SHAP) to predict the flue pressure and take targeted adjustment measures. First, the sintering process data were collected and processed. A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP + extremely randomized trees (ET). The prediction accuracy of the model within the error range of ±0.25 kPa was 92.63%. SHAP analysis was employed to improve the interpretability of the prediction model. The effects of various sintering operation parameters on flue pressure, the relationship between the numerical range of key operation parameters and flue pressure, the effect of operation parameter combinations on flue pressure, and the prediction process of the flue pressure prediction model on a single sample were analyzed. A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions. The operating parameter combination was then pushed. The flue pressure was increased by 5.87% during the verification process, achieving a good optimization effect.
Sinter is the core raw material for blast furnaces. Flue pressure, which is an important state parameter, affects sinter quality. In this paper, flue pressure prediction and optimization were studied based on the shapley additive explanation (SHAP) to predict the flue pressure and take targeted adjustment measures. First, the sintering process data were collected and processed. A flue pressure prediction model was then constructed after comparing different feature selection methods and model algorithms using SHAP + extremely randomized trees (ET). The prediction accuracy of the model within the error range of ±0.25 kPa was 92.63%. SHAP analysis was employed to improve the interpretability of the prediction model. The effects of various sintering operation parameters on flue pressure, the relationship between the numerical range of key operation parameters and flue pressure, the effect of operation parameter combinations on flue pressure, and the prediction process of the flue pressure prediction model on a single sample were analyzed. A flue pressure optimization module was also constructed and analyzed when the prediction satisfied the judgment conditions. The operating parameter combination was then pushed. The flue pressure was increased by 5.87% during the verification process, achieving a good optimization effect.
, Available online 12 June 2024,
https://doi.org/10.1007/s12613-024-2953-1
Abstract:
S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800°C at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate (PMS) for methylene blue (MB) degradation. The effects of two different mixing routes were identified on the MB degradation performance. Particularly, the catalyst obtained by the alcohol solvent evaporation (MOF-AEP) mixing route could degrade 95.60% MB (50 mg/L) within 4 min (degradation rate: K = 0.78 min–1), which was faster than that derived from the direct grinding method (MOF-DGP, 80.97%, K = 0.39 min–1). X-ray photoelectron spectroscopy revealed that the Co–S content of MOF-AEP (43.39at%) was less than that of MOF-DGP (54.73at%), and the proportion of C–S–C in MOF-AEP (13.56at%) was higher than that of MOF-DGP (10.67at%). Density functional theory calculations revealed that the adsorption energy of Co for PMS was −2.94 eV when sulfur was doped as C–S–C on the carbon skeleton, which was higher than that when sulfur was doped next to cobalt in the form of Co–S bond (−2.86 eV). Thus, the C–S–C sites might provide more contributions to activate PMS compared with Co–S. Furthermore, the degradation parameters, including pH and MOF-AEP dosage, were investigated. Finally, radical quenching experiments and electron paramagnetic resonance (EPR) measurements revealed that 1O2 might be the primary catalytic species, whereas · O2− might be the secondary one in degrading MB.
S and Co co-doped carbon catalysts were prepared via pyrolysis of MOF-71 and thiourea mixtures at 800°C at a mass ratio of MOF-71 to thiourea of 1:0.1 to effectively activate peroxymonosulfate (PMS) for methylene blue (MB) degradation. The effects of two different mixing routes were identified on the MB degradation performance. Particularly, the catalyst obtained by the alcohol solvent evaporation (MOF-AEP) mixing route could degrade 95.60% MB (50 mg/L) within 4 min (degradation rate: K = 0.78 min–1), which was faster than that derived from the direct grinding method (MOF-DGP, 80.97%, K = 0.39 min–1). X-ray photoelectron spectroscopy revealed that the Co–S content of MOF-AEP (43.39at%) was less than that of MOF-DGP (54.73at%), and the proportion of C–S–C in MOF-AEP (13.56at%) was higher than that of MOF-DGP (10.67at%). Density functional theory calculations revealed that the adsorption energy of Co for PMS was −2.94 eV when sulfur was doped as C–S–C on the carbon skeleton, which was higher than that when sulfur was doped next to cobalt in the form of Co–S bond (−2.86 eV). Thus, the C–S–C sites might provide more contributions to activate PMS compared with Co–S. Furthermore, the degradation parameters, including pH and MOF-AEP dosage, were investigated. Finally, radical quenching experiments and electron paramagnetic resonance (EPR) measurements revealed that 1O2 might be the primary catalytic species, whereas · O2− might be the secondary one in degrading MB.
, Available online 28 May 2024,
https://doi.org/10.1007/s12613-024-2944-2
Abstract:
Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude. To investigate the correlation between the rock mass properties and maximum horizontal stress, the three-dimensional (3D) stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted, a newly defined characteristic parameter CERP was proposed as an indicator for evaluating the structural properties of rock masses, and a fuzzy relation matrix was established using the information distribution method. The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth. There is no remarkable correlation between the elastic modulus, Poisson’s ratio and depth, and the distribution of data points is scattered and messy. Moreover, there is no obvious relationship between the rock quality designation (RQD) and depth. The maximum horizontal stress σH is a function of rock properties, showing a certain linear relationship with the CERP at the same depth. In addition, the overall change trend of σH determined by the established fuzzy identification method is to increase with the increase of CERP. The fuzzy identification method also demonstrates a relatively detailed local relationship between σH and CERP, and the predicted curve rises in a fluctuating way, which is in accord well with the measured stress data.
Understanding the mechanical properties of the lithologies is crucial to accurately determine the horizontal stress magnitude. To investigate the correlation between the rock mass properties and maximum horizontal stress, the three-dimensional (3D) stress tensors at 89 measuring points determined using an improved overcoring technique in nine mines in China were adopted, a newly defined characteristic parameter CERP was proposed as an indicator for evaluating the structural properties of rock masses, and a fuzzy relation matrix was established using the information distribution method. The results indicate that both the vertical stress and horizontal stress exhibit a good linear growth relationship with depth. There is no remarkable correlation between the elastic modulus, Poisson’s ratio and depth, and the distribution of data points is scattered and messy. Moreover, there is no obvious relationship between the rock quality designation (RQD) and depth. The maximum horizontal stress σH is a function of rock properties, showing a certain linear relationship with the CERP at the same depth. In addition, the overall change trend of σH determined by the established fuzzy identification method is to increase with the increase of CERP. The fuzzy identification method also demonstrates a relatively detailed local relationship between σH and CERP, and the predicted curve rises in a fluctuating way, which is in accord well with the measured stress data.
, Available online 28 May 2024,
https://doi.org/10.1007/s12613-024-2945-1
Abstract:
At present, the emerging solid-phase friction-based additive manufacturing technology, including friction rolling additive manufacturing (FRAM), can only manufacture simple single-pass components. In this study, multi-layer multi-pass FRAM-deposited aluminum alloy samples were successfully prepared using a non-shoulder tool head. The material flow behavior and microstructure of the overlapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum alloys. The results showed that a mechanical interlocking structure was formed between the adjacent layers and the adjacent passes in the overlapped center area. Repeated friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone, which made the recrystallization degree in the left and right edge zones of the overlapped zone the highest, followed by the overlapped center zone and the non-overlapped zone. The tensile strength of the overlapped zone exceeded 90% of that of the single-pass deposition sample. It is proved that although there are uneven grooves on the surface of the overlapping area during multi-layer and multi-pass deposition, they can be filled by the flow of materials during the deposition of the next layer, thus ensuring the dense microstructure and excellent mechanical properties of the overlapping area. The multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.
At present, the emerging solid-phase friction-based additive manufacturing technology, including friction rolling additive manufacturing (FRAM), can only manufacture simple single-pass components. In this study, multi-layer multi-pass FRAM-deposited aluminum alloy samples were successfully prepared using a non-shoulder tool head. The material flow behavior and microstructure of the overlapped zone between adjacent layers and passes during multi-layer multi-pass FRAM deposition were studied using the hybrid 6061 and 5052 aluminum alloys. The results showed that a mechanical interlocking structure was formed between the adjacent layers and the adjacent passes in the overlapped center area. Repeated friction and rolling of the tool head led to different degrees of lateral flow and plastic deformation of the materials in the overlapped zone, which made the recrystallization degree in the left and right edge zones of the overlapped zone the highest, followed by the overlapped center zone and the non-overlapped zone. The tensile strength of the overlapped zone exceeded 90% of that of the single-pass deposition sample. It is proved that although there are uneven grooves on the surface of the overlapping area during multi-layer and multi-pass deposition, they can be filled by the flow of materials during the deposition of the next layer, thus ensuring the dense microstructure and excellent mechanical properties of the overlapping area. The multi-layer multi-pass FRAM deposition overcomes the limitation of deposition width and lays the foundation for the future deposition of large-scale high-performance components.
, Available online 18 May 2024,
https://doi.org/10.1007/s12613-024-2937-1
Abstract:
Carbon can change the phase components of low-density steels and influence the mechanical properties. In this study, a new method to control the carbon content and avoid the formation of δ-ferrite by decarburization treatment was proposed. The microstructural changes and mechanical characteristics with carbon content induced by decarburization were systematically examined. Crussard–Jaoul (C–J) analysis was employed to examine the work hardening characteristics during the tensile test. During decarburization by heat treatments, the carbon content within the austenite phase decreased, while Mn and Al were almost unchanged; this made the steel with full austenite transform into the austenite and ferrite dual phase. Meanwhile, (Ti,V)C carbides existed in both matrix phase and the mole fraction almost the same. In addition, the formation of other carbides restrained. Carbon loss induced a decrease in strength due to the weakening of the carbon solid solution. For the steel with the single austinite, the deformation mode of austenite was the dislocation planar glide, resulting in the formation of microbands. For the dual-phase steel, the deformation occurred by the dislocation planar glide of austenite first, with the increase in strain, the cross slip of ferrite took place, forming dislocation cells in ferrite. At the late stage of deformation, the work hardening of austinite increased rapidly, while that of ferrite increased slightly.
Carbon can change the phase components of low-density steels and influence the mechanical properties. In this study, a new method to control the carbon content and avoid the formation of δ-ferrite by decarburization treatment was proposed. The microstructural changes and mechanical characteristics with carbon content induced by decarburization were systematically examined. Crussard–Jaoul (C–J) analysis was employed to examine the work hardening characteristics during the tensile test. During decarburization by heat treatments, the carbon content within the austenite phase decreased, while Mn and Al were almost unchanged; this made the steel with full austenite transform into the austenite and ferrite dual phase. Meanwhile, (Ti,V)C carbides existed in both matrix phase and the mole fraction almost the same. In addition, the formation of other carbides restrained. Carbon loss induced a decrease in strength due to the weakening of the carbon solid solution. For the steel with the single austinite, the deformation mode of austenite was the dislocation planar glide, resulting in the formation of microbands. For the dual-phase steel, the deformation occurred by the dislocation planar glide of austenite first, with the increase in strain, the cross slip of ferrite took place, forming dislocation cells in ferrite. At the late stage of deformation, the work hardening of austinite increased rapidly, while that of ferrite increased slightly.
, Available online 16 May 2024,
https://doi.org/10.1007/s12613-024-2935-3
Abstract:
This work reveals the significant effects of cobalt (Co) on the microstructure and impact toughness of as-quenched high-strength steels by experimental characterizations and thermo-kinetic analyses. The results show that the Co-bearing steel exhibits finer blocks and a lower ductile–brittle transition temperature than the steel without Co. Moreover, the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6. The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair. Furthermore, the addition of Co induces a larger transformation driving force and a lower bainite start temperature (BS), thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair. These findings would be instructive for the composition, microstructure design, and property optimization of high-strength steels.
This work reveals the significant effects of cobalt (Co) on the microstructure and impact toughness of as-quenched high-strength steels by experimental characterizations and thermo-kinetic analyses. The results show that the Co-bearing steel exhibits finer blocks and a lower ductile–brittle transition temperature than the steel without Co. Moreover, the Co-bearing steel reveals higher transformation rates at the intermediate stage with bainite volume fraction ranging from around 0.1 to 0.6. The improved impact toughness of the Co-bearing steel results from the higher dense block boundaries dominated by the V1/V2 variant pair. Furthermore, the addition of Co induces a larger transformation driving force and a lower bainite start temperature (BS), thereby contributing to the refinement of blocks and the increase of the V1/V2 variant pair. These findings would be instructive for the composition, microstructure design, and property optimization of high-strength steels.
, Available online 15 May 2024,
https://doi.org/10.1007/s12613-024-2933-5
Abstract:
This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy (HEA), YGdTbDyHo. Results indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains, with the alloy elements distributed homogeneously. Upon hydrogen absorption, the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed (HCP) structure to a high-entropy hydride with an faced-centered-cubic (FCC) structure without any secondary phase precipitated. The alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M (hydrogen atom/metal atom) at 723 K, with an enthalpy change (ΔH) of −141.09 kJ·mol−1 and an entropy change (ΔS) of −119.14 J·mol−1·K−1. The kinetic mechanism of hydrogen absorption was hydride nucleation and growth, with an apparent activation energy (Ea) of 20.90 kJ·mol−1. Without any activation, the YGdTbDyHo alloy could absorb hydrogen quickly (180 s at 923 K) with nearly no incubation period observed. The reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral interstices. These results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio, which can be used in the deuterium storage field.
This study investigated the microstructure and hydrogen absorption properties of a rare-earth high-entropy alloy (HEA), YGdTbDyHo. Results indicated that the YGdTbDyHo alloy had a microstructure of equiaxed grains, with the alloy elements distributed homogeneously. Upon hydrogen absorption, the phase structure of the HEA changed from a solid solution with an hexagonal-close-packed (HCP) structure to a high-entropy hydride with an faced-centered-cubic (FCC) structure without any secondary phase precipitated. The alloy demonstrated a maximum hydrogen storage capacity of 2.33 H/M (hydrogen atom/metal atom) at 723 K, with an enthalpy change (ΔH) of −141.09 kJ·mol−1 and an entropy change (ΔS) of −119.14 J·mol−1·K−1. The kinetic mechanism of hydrogen absorption was hydride nucleation and growth, with an apparent activation energy (Ea) of 20.90 kJ·mol−1. Without any activation, the YGdTbDyHo alloy could absorb hydrogen quickly (180 s at 923 K) with nearly no incubation period observed. The reason for the obtained value of 2.33 H/M was that the hydrogen atoms occupied both tetrahedral and octahedral interstices. These results demonstrate the potential application of HEAs as a high-capacity hydrogen storage material with a large H/M ratio, which can be used in the deuterium storage field.
, Available online 11 May 2024,
https://doi.org/10.1007/s12613-024-2931-7
Abstract:
Densely distributed coherent nanoparticles (DCN) in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously. All the routes to this end can be generally classified into the liquid–solid route and the solid–solid route. However, the formation of DCN structures in steel requires long processes and complex steps. So far, obtaining steel with coherent particle enhancement in a short time remains a bottleneck, and some necessary steps remain unavoidable. Here, we show a high-efficiency liquid-phase refining process reinforced by a dynamic magnetic field. Ti–Y–Mn–O particles had an average size of around (3.53 ± 1.21) nm and can be obtained in just around 180 s. These small nanoparticles were coherent with the matrix, implying no accumulated dislocations between the particles and the steel matrix. Our findings have a potential application for improving material machining capacity, creep resistance, and radiation resistance.
Densely distributed coherent nanoparticles (DCN) in steel matrix can enhance the work-hardening ability and ductility of steel simultaneously. All the routes to this end can be generally classified into the liquid–solid route and the solid–solid route. However, the formation of DCN structures in steel requires long processes and complex steps. So far, obtaining steel with coherent particle enhancement in a short time remains a bottleneck, and some necessary steps remain unavoidable. Here, we show a high-efficiency liquid-phase refining process reinforced by a dynamic magnetic field. Ti–Y–Mn–O particles had an average size of around (3.53 ± 1.21) nm and can be obtained in just around 180 s. These small nanoparticles were coherent with the matrix, implying no accumulated dislocations between the particles and the steel matrix. Our findings have a potential application for improving material machining capacity, creep resistance, and radiation resistance.
, Available online 11 May 2024,
https://doi.org/10.1007/s12613-024-2930-8
Abstract:
Carbon materials are widely recognized as highly promising electrode materials for various energy storage system applications. Coal tar residues (CTR), as a type of carbon-rich solid waste with high value-added utilization, are crucially important for the development of a more sustainable world. In this study, we employed a straightforward direct carbonization method within the temperature range of 700–1000°C to convert the worthless solid waste CTR into economically valuable carbon materials as anodes for potassium-ion batteries (PIBs). The effect of carbonization temperature on the microstructure and the potassium ions storage properties of CTR-derived carbons (CTRCs) were systematically explored by structural and morphological characterization, alongside electrochemical performances assessment. Based on the co-regulation between the turbine layers, crystal structure, pore structure, functional groups, and electrical conductivity of CTR-derived carbon carbonized at 900°C (CTRC-900H), the electrode material with high reversible capacity of 265.6 mAh g−1 at 50 mA·g−1, a desirable cycling stability with 93.8% capacity retention even after 100 cycles, and the remarkable rate performance for PIBs were obtained. Furthermore, cyclic voltammetry (CV) at different scan rates and galvanostatic intermittent titration technique (GITT) have been employed to explore the potassium ions storage mechanism and electrochemical kinetics of CTRCs. Results indicate that the electrode behavior is predominantly governed by surface-induced capacitive processes, particularly under high current densities, with the potassium storage mechanism characterized by an “adsorption–weak intercalation” mechanism. This work highlights the potential of CTR-based carbon as a promising electrode material category suitable for high-performance PIBs electrodes, while also provides valuable insights into the new avenues for the high value-added utilization of CTR.
Carbon materials are widely recognized as highly promising electrode materials for various energy storage system applications. Coal tar residues (CTR), as a type of carbon-rich solid waste with high value-added utilization, are crucially important for the development of a more sustainable world. In this study, we employed a straightforward direct carbonization method within the temperature range of 700–1000°C to convert the worthless solid waste CTR into economically valuable carbon materials as anodes for potassium-ion batteries (PIBs). The effect of carbonization temperature on the microstructure and the potassium ions storage properties of CTR-derived carbons (CTRCs) were systematically explored by structural and morphological characterization, alongside electrochemical performances assessment. Based on the co-regulation between the turbine layers, crystal structure, pore structure, functional groups, and electrical conductivity of CTR-derived carbon carbonized at 900°C (CTRC-900H), the electrode material with high reversible capacity of 265.6 mAh g−1 at 50 mA·g−1, a desirable cycling stability with 93.8% capacity retention even after 100 cycles, and the remarkable rate performance for PIBs were obtained. Furthermore, cyclic voltammetry (CV) at different scan rates and galvanostatic intermittent titration technique (GITT) have been employed to explore the potassium ions storage mechanism and electrochemical kinetics of CTRCs. Results indicate that the electrode behavior is predominantly governed by surface-induced capacitive processes, particularly under high current densities, with the potassium storage mechanism characterized by an “adsorption–weak intercalation” mechanism. This work highlights the potential of CTR-based carbon as a promising electrode material category suitable for high-performance PIBs electrodes, while also provides valuable insights into the new avenues for the high value-added utilization of CTR.
, Available online 8 May 2024,
https://doi.org/10.1007/s12613-024-2928-2
Abstract:
The local structure and thermophysical behavior of Mg–La liquid alloys were in-depth understood using deep potential molecular dynamic (DPMD) simulation driven via machine learning to promote the development of Mg–La alloys. The robustness of the trained deep potential (DP) model was thoroughly evaluated through several aspects, including root-mean-square errors (RMSEs), energy and force data, and structural information comparison results; the results indicate the carefully trained DP model is reliable. The component and temperature dependence of the local structure in the Mg–La liquid alloy was analyzed. The effect of Mg content in the system on the first coordination shell of the atomic pairs is the same as that of temperature. The pre-peak demonstrated in the structure factor indicates the presence of a medium-range ordered structure in the Mg–La liquid alloy, which is particularly pronounced in the 80at% Mg system and disappears at elevated temperatures. The density, self-diffusion coefficient, and shear viscosity for the Mg–La liquid alloy were predicted via DPMD simulation, the evolution patterns with Mg content and temperature were subsequently discussed, and a database was established accordingly. Finally, the mixing enthalpy and elemental activity of the Mg–La liquid alloy at 1200 K were reliably evaluated, which provides new guidance for related studies.
The local structure and thermophysical behavior of Mg–La liquid alloys were in-depth understood using deep potential molecular dynamic (DPMD) simulation driven via machine learning to promote the development of Mg–La alloys. The robustness of the trained deep potential (DP) model was thoroughly evaluated through several aspects, including root-mean-square errors (RMSEs), energy and force data, and structural information comparison results; the results indicate the carefully trained DP model is reliable. The component and temperature dependence of the local structure in the Mg–La liquid alloy was analyzed. The effect of Mg content in the system on the first coordination shell of the atomic pairs is the same as that of temperature. The pre-peak demonstrated in the structure factor indicates the presence of a medium-range ordered structure in the Mg–La liquid alloy, which is particularly pronounced in the 80at% Mg system and disappears at elevated temperatures. The density, self-diffusion coefficient, and shear viscosity for the Mg–La liquid alloy were predicted via DPMD simulation, the evolution patterns with Mg content and temperature were subsequently discussed, and a database was established accordingly. Finally, the mixing enthalpy and elemental activity of the Mg–La liquid alloy at 1200 K were reliably evaluated, which provides new guidance for related studies.
, Available online 19 April 2024,
https://doi.org/10.1007/s12613-024-2918-4
Abstract:
Microstructure, texture, and mechanical properties of the extruded Mg–2.49Nd–1.82Gd–0.2Zn–0.2Zr alloy were investigated at different extrusion temperatures (260 and 320°C), extrusion ratios (10:1, 15:1, and 30:1), and extrusion speeds (3 and 6 mm/s). The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy, and the second phase showed streamline distribution along the extrusion direction (ED). With extrusion temperature increased from 260 to 320°C, the microstructure, texture, and mechanical properties of alloys changed slightly. The dynamic recrystallization (DRX) degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1, and the strength gradually decreased but elongation (EL) increased. With the extrusion speed increased from 3 to 6 mm/s, the grain sizes and DRX degree increased significantly, and the samples presented the typical <\begin{document}$2\bar{1}\bar{1}1 $\end{document} \begin{document}$ 11\bar{2}3 $\end{document}
Microstructure, texture, and mechanical properties of the extruded Mg–2.49Nd–1.82Gd–0.2Zn–0.2Zr alloy were investigated at different extrusion temperatures (260 and 320°C), extrusion ratios (10:1, 15:1, and 30:1), and extrusion speeds (3 and 6 mm/s). The experimental results exhibited that the grain sizes after extrusion were much finer than that of the homogenized alloy, and the second phase showed streamline distribution along the extrusion direction (ED). With extrusion temperature increased from 260 to 320°C, the microstructure, texture, and mechanical properties of alloys changed slightly. The dynamic recrystallization (DRX) degree and grain sizes enhanced as the extrusion ratio increased from 10:1 to 30:1, and the strength gradually decreased but elongation (EL) increased. With the extrusion speed increased from 3 to 6 mm/s, the grain sizes and DRX degree increased significantly, and the samples presented the typical <
, Available online 16 April 2024,
https://doi.org/10.1007/s12613-024-2912-x
Abstract:
Pt-based nanocatalysts offer excellent prospects for various industries. However, the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable challenge. In this study, nanocatalysts with ultralow Pt content, excellent performance, and carbon black as support were prepared through in-situ synthesis. These ~2-nm particles uniformly and stably dispersed on carbon black because of the strong s–p–d orbital hybridizations between carbon black and Pt, which suppressed the agglomeration of Pt ions. This unique structure is beneficial for the hydrogen evolution reaction. The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction, exhibiting a potential of 100 mV at 100 mA·cm−2, which is comparable to those of commercial Pt/C catalysts. Mass activity (1.61 A/mg) was four times that of a commercial Pt/C catalyst (0.37 A/mg). The ultralow Pt loading (6.84wt%) paves the way for the development of next-generation electrocatalysts.
Pt-based nanocatalysts offer excellent prospects for various industries. However, the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable challenge. In this study, nanocatalysts with ultralow Pt content, excellent performance, and carbon black as support were prepared through in-situ synthesis. These ~2-nm particles uniformly and stably dispersed on carbon black because of the strong s–p–d orbital hybridizations between carbon black and Pt, which suppressed the agglomeration of Pt ions. This unique structure is beneficial for the hydrogen evolution reaction. The catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction, exhibiting a potential of 100 mV at 100 mA·cm−2, which is comparable to those of commercial Pt/C catalysts. Mass activity (1.61 A/mg) was four times that of a commercial Pt/C catalyst (0.37 A/mg). The ultralow Pt loading (6.84wt%) paves the way for the development of next-generation electrocatalysts.
, Available online 16 April 2024,
https://doi.org/10.1007/s12613-024-2913-9
Abstract:
Currently, the Al2O3 content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%, making it challenging to overcome this limitation. Unlike most studies that concentrated on managing the MgO/Al2O3 ratio or basicity, this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO–MgO–Al2O3–SiO2 slag system, providing theoretical guidance and data to facilitate the application of high-alumina ores. The results revealed that the viscosity first decreased and then increased with higher MgO substitution, reaching a minimum at 15mol% MgO concentration. Fourier transform infrared spectroscopy (FTIR) results found that the depths of the troughs representing [SiO4] tetrahedra, [AlO4] tetrahedra, and Si–O–Al bending became progressively deeper with increased MgO substitution. Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the\begin{document}$ {X_{{{\text{Q}}^3}}}{\text{/}}{X_{{{\text{Q}}^2}}} $\end{document} \begin{document}$ {X_{{{\text{Q}}^i}}} $\end{document}
Currently, the Al2O3 content in the high-alumina slag systems within blast furnaces is generally limited to 16wt%–18.5wt%, making it challenging to overcome this limitation. Unlike most studies that concentrated on managing the MgO/Al2O3 ratio or basicity, this paper explored the effect of equimolar substitution of MgO for CaO on the viscosity and structure of a high-alumina CaO–MgO–Al2O3–SiO2 slag system, providing theoretical guidance and data to facilitate the application of high-alumina ores. The results revealed that the viscosity first decreased and then increased with higher MgO substitution, reaching a minimum at 15mol% MgO concentration. Fourier transform infrared spectroscopy (FTIR) results found that the depths of the troughs representing [SiO4] tetrahedra, [AlO4] tetrahedra, and Si–O–Al bending became progressively deeper with increased MgO substitution. Deconvolution of the Raman spectra showed that the average number of bridging oxygens per Si atom and the
, Available online 16 April 2024,
https://doi.org/10.1007/s12613-024-2914-8
Abstract:
The influence of Nb–V microalloying on the hot deformation behavior and microstructures of medium Mn steel (MMS) was investigated by uniaxial hot compression tests. By establishing the constitutive equations for simulating the measured flow curves, we successfully constructed deformation activation energy (Q) maps and processing maps for identifying the region of flow instability. We concluded the following consequences of Nb–V alloying for MMS. (i) The critical strain increases, and the increment diminishes with the increasing deformation temperature, suggesting that NbC precipitates more efficiently retard dynamic recrystallization (DRX) in MMS compared with solute Nb. (ii) The deformation activation energy of MMS is significantly increased and even higher than that of high Mn steels, suggesting that its ability to retard DRX is greater than that of the high Mn content. (iii) The hot workability of MMS is improved by narrowing the hot processing window for the unstable flow stress, in which fine recrystallized and coarse unrecrystallized grains are present.
The influence of Nb–V microalloying on the hot deformation behavior and microstructures of medium Mn steel (MMS) was investigated by uniaxial hot compression tests. By establishing the constitutive equations for simulating the measured flow curves, we successfully constructed deformation activation energy (Q) maps and processing maps for identifying the region of flow instability. We concluded the following consequences of Nb–V alloying for MMS. (i) The critical strain increases, and the increment diminishes with the increasing deformation temperature, suggesting that NbC precipitates more efficiently retard dynamic recrystallization (DRX) in MMS compared with solute Nb. (ii) The deformation activation energy of MMS is significantly increased and even higher than that of high Mn steels, suggesting that its ability to retard DRX is greater than that of the high Mn content. (iii) The hot workability of MMS is improved by narrowing the hot processing window for the unstable flow stress, in which fine recrystallized and coarse unrecrystallized grains are present.
, Available online 2 April 2024,
https://doi.org/10.1007/s12613-024-2896-6
Abstract:
During the continuous casting process of high-Mn high-Al steels, various types of gases such as Ar need to escape through the top of the mold. In which, the behavior of bubbles traversing the liquid slag serves as a restrictive link, closely associated with viscosity and the thickness of liquid slag. In contrast to two-dimensional surface observation, three-dimensional (3D) analysis method can offer a more intuitive, accurate, and comprehensive information. Therefore, this study employs a 3D X-ray microscope (3D-XRM) to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag, different temperatures, and different holding times. The results indicate that as basicity of slag increases from 0.52 to 1.03, temperature increases from 1423 to 1573 K, the viscosity of slag decreases, the floating rate of bubbles increases. In addition, when holding time increases from 10 to 30 s, the bubbles floating distance increases, and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases. In one word, increasing the basicity, temperature, and holding time leading to an increase in the removal rate of bubbles especially for the large. These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.
During the continuous casting process of high-Mn high-Al steels, various types of gases such as Ar need to escape through the top of the mold. In which, the behavior of bubbles traversing the liquid slag serves as a restrictive link, closely associated with viscosity and the thickness of liquid slag. In contrast to two-dimensional surface observation, three-dimensional (3D) analysis method can offer a more intuitive, accurate, and comprehensive information. Therefore, this study employs a 3D X-ray microscope (3D-XRM) to obtained spatial distribution and 3D morphological characteristics of residual bubbles in mold flux under different basicity of liquid slag, different temperatures, and different holding times. The results indicate that as basicity of slag increases from 0.52 to 1.03, temperature increases from 1423 to 1573 K, the viscosity of slag decreases, the floating rate of bubbles increases. In addition, when holding time increases from 10 to 30 s, the bubbles floating distance increases, and the volume fraction and average equivalent sphere diameter of the bubbles solidified in the mold flux gradually decreases. In one word, increasing the basicity, temperature, and holding time leading to an increase in the removal rate of bubbles especially for the large. These findings of bubbles escape behavior provide valuable insights into optimizing low basicity mold flux for high-Mn high-Al steels.
, Available online 2 April 2024,
https://doi.org/10.1007/s12613-024-2898-4
Abstract:
With the continuous increase in the disposal volume of spent lithium-ion batteries (LIBs), properly recycling spent LIBs has become essential for the advancement of the circular economy. This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials. The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free, model-fitting, and Z(α) function (α is conversion rate). Results indicated that the reaction was dominated by the first-order (F1) model when the conversion rate was less than or equal to 0.5 and shifted to the second-order (F2) model when the conversion rate exceeded 0.5. Optimal conditions were determined by thoroughly investigating the effects of roasting temperature, roasting time, and the mass ratio of NH4Cl to LiCoO2. Under the optimal conditions, namely 400°C, 20 min, and NH4Cl/LiCoO2 mass ratio of 3:1, the leaching efficiency of Li and Co reached 99.43% and 99.05%, respectively. Analysis of the roasted products revealed that valuable metals in LiCoO2 transformed into CoCl2 and LiCl. Furthermore, the reaction mechanism was elucidated, providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective. This technology can guide the development of LIB recycling processes with low energy consumption, low secondary pollution, high recovery efficiency, and high added value.
With the continuous increase in the disposal volume of spent lithium-ion batteries (LIBs), properly recycling spent LIBs has become essential for the advancement of the circular economy. This study presents a systematic analysis of the chlorination roasting kinetics and proposes a new two-step chlorination roasting process that integrates thermodynamics for the recycling of LIB cathode materials. The activation energy for the chloride reaction was 88.41 kJ/mol according to thermogravimetric analysis–derivative thermogravimetry data obtained by using model-free, model-fitting, and Z(α) function (α is conversion rate). Results indicated that the reaction was dominated by the first-order (F1) model when the conversion rate was less than or equal to 0.5 and shifted to the second-order (F2) model when the conversion rate exceeded 0.5. Optimal conditions were determined by thoroughly investigating the effects of roasting temperature, roasting time, and the mass ratio of NH4Cl to LiCoO2. Under the optimal conditions, namely 400°C, 20 min, and NH4Cl/LiCoO2 mass ratio of 3:1, the leaching efficiency of Li and Co reached 99.43% and 99.05%, respectively. Analysis of the roasted products revealed that valuable metals in LiCoO2 transformed into CoCl2 and LiCl. Furthermore, the reaction mechanism was elucidated, providing insights for the establishment of a novel low-temperature chlorination roasting technology based on a crystal structure perspective. This technology can guide the development of LIB recycling processes with low energy consumption, low secondary pollution, high recovery efficiency, and high added value.
Effect of lamellarization on the microstructure and mechanical properties of marine 10Ni5CrMoV steel
, Available online 2 April 2024,
https://doi.org/10.1007/s12613-024-2897-5
Abstract:
Multistage heat treatment involving quenching (Q), lamellarizing (L), and tempering (T) is applied to marine 10Ni5CrMoV steel. The microstructure and mechanical properties were studied by multiscale characterizations, and the kinetics of reverse austenite transformation, strain hardening behavior, and toughening mechanism were further investigated. The lamellarized specimens possess low yield strength but high toughness, especially cryogenic toughness. Lamellarization leads to the development of film-like reversed austenite at the martensite block and lath boundaries, refining the martensite structure and lowering the equivalent grain size. Kinetic analysis of austenite reversion based on the JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite, and the maximum transformation of reversed austenite is reached at the peak temperature (750°C). The strain hardening behavior based on the modified Crussard–Jaoul analysis indicates that the reversed austenite obtained from lamellarization reduces the proportion of martensite, significantly hindering crack propagation via martensitic transformation during the deformation. As a consequence, the QLT specimens exhibit high machinability and low yield strength. Compared with the QT specimen, the ductile–brittle transition temperature of the QLT specimens decreases from −116 to −130°C due to the low equivalent grain size and reversed austenite, which increases the cleavage force required for crack propagation and absorbs the energy of external load, respectively. This work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel and lays a theoretical foundation for its industrial application and comprehensive performance improvement.
Multistage heat treatment involving quenching (Q), lamellarizing (L), and tempering (T) is applied to marine 10Ni5CrMoV steel. The microstructure and mechanical properties were studied by multiscale characterizations, and the kinetics of reverse austenite transformation, strain hardening behavior, and toughening mechanism were further investigated. The lamellarized specimens possess low yield strength but high toughness, especially cryogenic toughness. Lamellarization leads to the development of film-like reversed austenite at the martensite block and lath boundaries, refining the martensite structure and lowering the equivalent grain size. Kinetic analysis of austenite reversion based on the JMAK model shows that the isothermal transformation is dominated by the growth of reversed austenite, and the maximum transformation of reversed austenite is reached at the peak temperature (750°C). The strain hardening behavior based on the modified Crussard–Jaoul analysis indicates that the reversed austenite obtained from lamellarization reduces the proportion of martensite, significantly hindering crack propagation via martensitic transformation during the deformation. As a consequence, the QLT specimens exhibit high machinability and low yield strength. Compared with the QT specimen, the ductile–brittle transition temperature of the QLT specimens decreases from −116 to −130°C due to the low equivalent grain size and reversed austenite, which increases the cleavage force required for crack propagation and absorbs the energy of external load, respectively. This work provides an idea to improve the cryogenic toughness of marine 10Ni5CrMoV steel and lays a theoretical foundation for its industrial application and comprehensive performance improvement.
, Available online 22 March 2024,
https://doi.org/10.1007/s12613-024-2890-z
Abstract:
Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation–desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu1.81S/nitrogen-doped carbon frameworks (Cu1.81S/NC) are synthesized by the simple and facile sol–gel and annealing processes, which can accommodate the volumetric expansion of Cu1.81S nanoparticles and accelerate the transmission of ions and electrons during Na+ insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh·g−1 at 20.0 A·g−1) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10.0 A·g−1) for SIBs. Moreover, the Na-ion full cells coupled with Na3V2(PO4)3/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g−1 at 5.0 A·g−1 and long-cycle performance with the 86.9% capacity retention at 2.0 A·g−1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.
Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation–desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu1.81S/nitrogen-doped carbon frameworks (Cu1.81S/NC) are synthesized by the simple and facile sol–gel and annealing processes, which can accommodate the volumetric expansion of Cu1.81S nanoparticles and accelerate the transmission of ions and electrons during Na+ insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh·g−1 at 20.0 A·g−1) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10.0 A·g−1) for SIBs. Moreover, the Na-ion full cells coupled with Na3V2(PO4)3/C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g−1 at 5.0 A·g−1 and long-cycle performance with the 86.9% capacity retention at 2.0 A·g−1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.
, Available online 21 March 2024,
https://doi.org/10.1007/s12613-024-2888-6
Abstract:
In recent years, medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances. By controlling reasonable elemental composition and processing parameters, the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower costs. In this paper, a FeCoNi medium entropy alloy precursor was prepared via sol–gel and co-precipitation methods, respectively, and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction. The phases and magnetic properties of FeCoNi medium entropy alloy were investigated. Results showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500°C. Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction. The alloy prepared by hydrogen reduction was uniform and showed a relatively high purity. Moreover, the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.
In recent years, medium entropy alloys have become a research hotspot due to their excellent physical and chemical performances. By controlling reasonable elemental composition and processing parameters, the medium entropy alloys can exhibit similar properties to high entropy alloys and have lower costs. In this paper, a FeCoNi medium entropy alloy precursor was prepared via sol–gel and co-precipitation methods, respectively, and FeCoNi medium entropy alloys were prepared by carbothermal and hydrogen reduction. The phases and magnetic properties of FeCoNi medium entropy alloy were investigated. Results showed that FeCoNi medium entropy alloy was produced by carbothermal and hydrogen reduction at 1500°C. Some carbon was detected in the FeCoNi medium entropy alloy prepared by carbothermal reduction. The alloy prepared by hydrogen reduction was uniform and showed a relatively high purity. Moreover, the hydrogen reduction product exhibited better saturation magnetization and lower coercivity.
, Available online 15 March 2024,
https://doi.org/10.1007/s12613-024-2882-z
Abstract:
High pressure die casting (HPDC) AlSi10MnMg alloy castings are widely used in the automobile industry. Mg can optimize the mechanical properties of castings through heat treatment, while the release of thermal stress arouses the deformation of large integrated die-castings. Herein, the development of non-heat treatment Al alloys is becoming the hot topic. In addition, HPDC contains externally solidified crystals (ESCs), which are detrimental to the mechanical properties of castings. To achieve high strength and toughness of non-heat treatment die-casting Al–Si alloy, we used AlSi9Mn alloy as matrix with the introduction of Zr, Ti, Nb, and Ce. Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation. Our results reveal that the addition of Ti increased ESCs’ size and porosity, while the introduction of Nb refined ESCs and decreased porosity. Meanwhile, large-sized Al3(Zr,Ti) phases formed and degraded the mechanical properties. Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.
High pressure die casting (HPDC) AlSi10MnMg alloy castings are widely used in the automobile industry. Mg can optimize the mechanical properties of castings through heat treatment, while the release of thermal stress arouses the deformation of large integrated die-castings. Herein, the development of non-heat treatment Al alloys is becoming the hot topic. In addition, HPDC contains externally solidified crystals (ESCs), which are detrimental to the mechanical properties of castings. To achieve high strength and toughness of non-heat treatment die-casting Al–Si alloy, we used AlSi9Mn alloy as matrix with the introduction of Zr, Ti, Nb, and Ce. Their influences on ESCs and mechanical properties were systematically investigated through three-dimensional reconstruction and thermodynamic simulation. Our results reveal that the addition of Ti increased ESCs’ size and porosity, while the introduction of Nb refined ESCs and decreased porosity. Meanwhile, large-sized Al3(Zr,Ti) phases formed and degraded the mechanical properties. Subsequent introduction of Ce resulted in the poisoning effect and reduced mechanical properties.
, Available online 7 March 2024,
https://doi.org/10.1007/s12613-024-2873-0
Abstract:
The utilization of iron coke provides a green pathway for low-carbon ironmaking. To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification, the effect of iron ore on the microstructure of iron coke was investigated. Furthermore, a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method. The findings indicate that compared to coke, iron coke exhibits an augmentation in micropores and specific surface area, and the micropores further extend and interconnect. This provides more adsorption sites for CO2 molecules during the gasification process, resulting in a reduction in the initial gasification temperature of iron coke. Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke. The metallic iron reduced from iron ore is embedded in the carbon matrix, reducing the orderliness of the carbon structure, which is primarily responsible for the heightened reactivity of the carbon atoms. The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure. Moreover, as the proportion of iron ore increases, the activation energy for the carbon gasification gradually decreases, from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.
The utilization of iron coke provides a green pathway for low-carbon ironmaking. To uncover the influence mechanism of iron ore on the behavior and kinetics of iron coke gasification, the effect of iron ore on the microstructure of iron coke was investigated. Furthermore, a comparative study of the gasification reactions between iron coke and coke was conducted through non-isothermal thermogravimetric method. The findings indicate that compared to coke, iron coke exhibits an augmentation in micropores and specific surface area, and the micropores further extend and interconnect. This provides more adsorption sites for CO2 molecules during the gasification process, resulting in a reduction in the initial gasification temperature of iron coke. Accelerating the heating rate in non-isothermal gasification can enhance the reactivity of iron coke. The metallic iron reduced from iron ore is embedded in the carbon matrix, reducing the orderliness of the carbon structure, which is primarily responsible for the heightened reactivity of the carbon atoms. The kinetic study indicates that the random pore model can effectively represent the gasification process of iron coke due to its rich pore structure. Moreover, as the proportion of iron ore increases, the activation energy for the carbon gasification gradually decreases, from 246.2 kJ/mol for coke to 192.5 kJ/mol for iron coke 15wt%.
, Available online 23 February 2024,
https://doi.org/10.1007/s12613-024-2860-5
Abstract:
The atmospheric corrosion monitoring (ACM) technique has been widely employed to track the real-time corrosion behavior of metal materials. However, limited studies have applied ACM to the corrosion protection properties of organic coatings. This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors, both applied on ACM sensors, to observe their corrosion protection properties over time. Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments, which allowed for monitoring galvanic corrosion currents in real-time. Throughout the corrosion tests, the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating. The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis. This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings. Compared with the blank epoxy coating, the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.
The atmospheric corrosion monitoring (ACM) technique has been widely employed to track the real-time corrosion behavior of metal materials. However, limited studies have applied ACM to the corrosion protection properties of organic coatings. This study compared a bare epoxy coating with one containing zinc phosphate corrosion inhibitors, both applied on ACM sensors, to observe their corrosion protection properties over time. Coatings with artificial damage via scratches were exposed to immersion and alternating dry and wet environments, which allowed for monitoring galvanic corrosion currents in real-time. Throughout the corrosion tests, the ACM currents of the zinc phosphate/epoxy coating were considerably lower than those of the blank epoxy coating. The trend in ACM current variations closely matched the results obtained from regular electrochemical tests and surface analysis. This alignment highlights the potential of the ACM technique in evaluating the corrosion protection capabilities of organic coatings. Compared with the blank epoxy coating, the zinc phosphate/epoxy coating showed much-decreased ACM current values that confirmed the effective inhibition of zinc phosphate against steel corrosion beneath the damaged coating.
, Available online 6 February 2024,
https://doi.org/10.1007/s12613-024-2849-0
Abstract:
Electromagnetic interference, which necessitates the rapid advancement of substances with exceptional capabilities for absorbing electromagnetic waves, is of urgent concern in contemporary society. In this work, CoFe2O4/residual carbon from coal gasification fine slag (CFO/RC) composites were created using a novel hydrothermal method. Various mechanisms for microwave absorption, including conductive loss, natural resonance, interfacial dipole polarization, and magnetic flux loss, are involved in these composites. Consequently, compared with pure residual carbon materials, this composite offers superior capabilities in microwave absorption. At 7.76 GHz, the CFO/RC-2 composite achieves an impressive minimum reflection loss (RLmin) of −43.99 dB with a thickness of 2.44 mm. Moreover, CFO/RC-3 demonstrates an effective absorption bandwidth (EAB) of up to 4.16 GHz, accompanied by a thickness of 1.18 mm. This study revealed the remarkable capability of the composite to diminish electromagnetic waves, providing a new generation method for microwave absorbing materials of superior quality.
Electromagnetic interference, which necessitates the rapid advancement of substances with exceptional capabilities for absorbing electromagnetic waves, is of urgent concern in contemporary society. In this work, CoFe2O4/residual carbon from coal gasification fine slag (CFO/RC) composites were created using a novel hydrothermal method. Various mechanisms for microwave absorption, including conductive loss, natural resonance, interfacial dipole polarization, and magnetic flux loss, are involved in these composites. Consequently, compared with pure residual carbon materials, this composite offers superior capabilities in microwave absorption. At 7.76 GHz, the CFO/RC-2 composite achieves an impressive minimum reflection loss (RLmin) of −43.99 dB with a thickness of 2.44 mm. Moreover, CFO/RC-3 demonstrates an effective absorption bandwidth (EAB) of up to 4.16 GHz, accompanied by a thickness of 1.18 mm. This study revealed the remarkable capability of the composite to diminish electromagnetic waves, providing a new generation method for microwave absorbing materials of superior quality.
, Available online 12 January 2024,
https://doi.org/10.1007/s12613-024-2828-5
Abstract:
This study aimed to investigate the effect of varying pyrite (Py) content on copper (Cu) in the presence of different regrinding conditions, which were altered using different types of grinding media: iron, ceramic balls, and their mixture, followed by flotation in the cleaner stage. The flotation performance of rough Cu concentrate can be improved by changing the regrinding conditions based on the Py content. Scanning electron microscopy, X-ray spectrometry, ethylenediaminetetraacetic acid disodium salt extraction, and X-ray photoelectron spectroscopy studies illustrated that when the Py content was high, the use of iron media in regrinding promoted the generation of hydrophilic FeOOH on the surface of Py and improved the Cu grade. The ceramic medium with a low Py content prevented excessive FeOOH from covering the surface of chalcopyrite (Cpy). Electrochemical studies further showed that the galvanic corrosion current of Cpy–Py increased with the addition of Py and became stronger with the participation of iron media.
This study aimed to investigate the effect of varying pyrite (Py) content on copper (Cu) in the presence of different regrinding conditions, which were altered using different types of grinding media: iron, ceramic balls, and their mixture, followed by flotation in the cleaner stage. The flotation performance of rough Cu concentrate can be improved by changing the regrinding conditions based on the Py content. Scanning electron microscopy, X-ray spectrometry, ethylenediaminetetraacetic acid disodium salt extraction, and X-ray photoelectron spectroscopy studies illustrated that when the Py content was high, the use of iron media in regrinding promoted the generation of hydrophilic FeOOH on the surface of Py and improved the Cu grade. The ceramic medium with a low Py content prevented excessive FeOOH from covering the surface of chalcopyrite (Cpy). Electrochemical studies further showed that the galvanic corrosion current of Cpy–Py increased with the addition of Py and became stronger with the participation of iron media.
, Available online 2 July 2024,
https://doi.org/10.1007/s12613-024-2966-9
Abstract:
Calcium ferrite (CF) is recognized as a potential green and efficient functional material because of its advantages of magnetism, electrochemistry, catalysis, and biocompatibility in the fields of materials chemistry, environmental engineering, and biomedicine. Therefore, the obtained research results need to be systematically summarized, and new perspectives on CF and its composite materials need to be analyzed. Based on the presented studies of CF and its composite materials, the types and structures of the crystal are summarized. In addition, the current application technologies and theoretical mechanisms with various properties in different fields are elucidated. Moreover, the various preparation methods of CF and its composite materials are elaborated in detail. Most importantly, the advantages and disadvantages of the synthesis methods of CF and its composite materials are discussed, and the existing problems and emerging challenges in practical production are identified. Furthermore, the key future research directions of CF and its composite materials have been prospected from the potential application technologies to provide references for its synthesis and efficient utilization.
Calcium ferrite (CF) is recognized as a potential green and efficient functional material because of its advantages of magnetism, electrochemistry, catalysis, and biocompatibility in the fields of materials chemistry, environmental engineering, and biomedicine. Therefore, the obtained research results need to be systematically summarized, and new perspectives on CF and its composite materials need to be analyzed. Based on the presented studies of CF and its composite materials, the types and structures of the crystal are summarized. In addition, the current application technologies and theoretical mechanisms with various properties in different fields are elucidated. Moreover, the various preparation methods of CF and its composite materials are elaborated in detail. Most importantly, the advantages and disadvantages of the synthesis methods of CF and its composite materials are discussed, and the existing problems and emerging challenges in practical production are identified. Furthermore, the key future research directions of CF and its composite materials have been prospected from the potential application technologies to provide references for its synthesis and efficient utilization.
, Available online 26 June 2024,
https://doi.org/10.1007/s12613-024-2961-1
Abstract:
As a mathematical analysis method, fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties. Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions. Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces. However, fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials. From the perspective of two-dimensional planes and three-dimensional curved surfaces, this paper reviews the current research status of the fractal analysis of metal precipitate interfaces, metal grain boundary interfaces, metal-deposited film surfaces, metal fracture surfaces, metal machined surfaces, and metal wear surfaces. The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized. Starting from three perspectives of fractal analysis, namely, research scope, image acquisition methods, and calculation methods, this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed. It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.
As a mathematical analysis method, fractal analysis can be used to quantitatively describe irregular shapes with self-similar or self-affine properties. Fractal analysis has been used to characterize the shapes of metal materials at various scales and dimensions. Conventional methods make it difficult to quantitatively describe the relationship between the regular characteristics and properties of metal material surfaces and interfaces. However, fractal analysis can be used to quantitatively describe the shape characteristics of metal materials and to establish the quantitative relationships between the shape characteristics and various properties of metal materials. From the perspective of two-dimensional planes and three-dimensional curved surfaces, this paper reviews the current research status of the fractal analysis of metal precipitate interfaces, metal grain boundary interfaces, metal-deposited film surfaces, metal fracture surfaces, metal machined surfaces, and metal wear surfaces. The relationship between the fractal dimensions and properties of metal material surfaces and interfaces is summarized. Starting from three perspectives of fractal analysis, namely, research scope, image acquisition methods, and calculation methods, this paper identifies the direction of research on fractal analysis of metal material surfaces and interfaces that need to be developed. It is believed that revealing the deep influence mechanism between the fractal dimensions and properties of metal material surfaces and interfaces will be the key research direction of the fractal analysis of metal materials in the future.
, Available online 19 April 2024,
https://doi.org/10.1007/s12613-024-2923-7
Abstract:
Solvent extraction, a separation and purification technology, is crucial in critical metal metallurgy. Organic solvents commonly used in solvent extraction exhibit disadvantages, such as high volatility, high toxicity, and flammability, causing a spectrum of hazards to human health and environmental safety. Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed, including ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages, namely, low toxicity, degradability, and low cost. In this critical review, their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research have been systematically described. Subsequently, the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized. Finally, future opportunities and challenges of DESs were explored in the current research area. In conclusion, this review provides valuable insights for improving our overall understanding of DESs, and it holds important potential for expanding separation and purification applications in critical metal metallurgy.
Solvent extraction, a separation and purification technology, is crucial in critical metal metallurgy. Organic solvents commonly used in solvent extraction exhibit disadvantages, such as high volatility, high toxicity, and flammability, causing a spectrum of hazards to human health and environmental safety. Neoteric solvents have been recognized as potential alternatives to these harmful organic solvents. In the past two decades, several neoteric solvents have been proposed, including ionic liquids (ILs) and deep eutectic solvents (DESs). DESs have gradually become the focus of green solvents owing to several advantages, namely, low toxicity, degradability, and low cost. In this critical review, their classification, formation mechanisms, preparation methods, characterization technologies, and special physicochemical properties based on the most recent advancements in research have been systematically described. Subsequently, the major separation and purification applications of DESs in critical metal metallurgy were comprehensively summarized. Finally, future opportunities and challenges of DESs were explored in the current research area. In conclusion, this review provides valuable insights for improving our overall understanding of DESs, and it holds important potential for expanding separation and purification applications in critical metal metallurgy.
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